Users Read Help Manuals Like an Encyclopedia, Not a Novel
http://www.idratherbewriting.com/2008/09/19/users-read-help-manuals-like-an-encyclopedia-not-a-novel/

Johnson, Tom H.
I'd Rather Be Writing
2008

Abstract:

Users turn to help to look for a specific question, just as someone consults an encyclopedia for a specific question. No one reads the entire encyclopedia/manual, nor is anyone expected to. Well-written encyclopedias allow users to find information through indexes, tables of contents, alphabetical organization, and search fields.